1. Field of the Invention
This invention relates to ductwork for ventilation systems which supply temperature controlled air to an enclosed room. More particularly, the present invention pertains to low temperature ductwork for commercial structures.
2. Prior Art
With the development of low temperature delivery systems for commercial applications, new demands are being imposed on existing ductwork. Whereas traditional refrigeration units cooled the air to a chilled condition which required movement of substantial volumes of air through a room to maintain cool temperatures, newer systems are supplying super-cooled air which cools the room with less air movement. By reducing the air temperature at the cooling coils to near freezing, less air is required to cool a room. This permits the use of less power and lower capacity systems. These and other factors translate into substantial cost savings for air conditioning services.
In order to maintain the efficiency of such low temperature delivery systems, enhanced insulation is required on the ductwork. Typically, fiberglass is wrapped around the duct at sufficient thickness to produce the desired R- factor. A problem arises at joints where leaks of cold air occur. Such leaks result in condensation and erosion of the fiberglass, thereby damaging the insulation material adjacent to the leak. This then increases formation of condensation and temperature loss, further extending the damage to the ductwork and insulative shield.
Improved ductwork with higher quality interconnection components, refined attachment of insulation and enhanced materials selection is able to solve the problem; however, the cost of these improvements makes the cost savings for the low temperature system less appealing. This is particularly true where construction of prior art ventilation systems involve ductwork that constitutes little more than a cheap aluminum tube with a layer of fiberglass batting wrapped around it. Although long term energy savings dwarf the initial savings realized with the installation of a low cost air delivery system, competition for construction will favor the lower capital cost. Indeed, a lower initial construction cost can mean the difference between a contractor winning a bid and losing the total construction package. Contractor will therefore tend to cut costs by installing inexpensive ductwork.
What is needed is a low temperature air delivery system that does not involve use of expensive ductwork, yet does not compromise the effective and complete insulation required.